Scotland holds the largest extent of raised peat bogs in good condition of any Member State. Since the start of the 19th Century the extent of primary, active, lowland raised bog in the UK has decreased by 85%.
Raised bogs, as their name suggests, rise above the landscape. When the glaciers retreated from Scotland at the end of the last glaciation 10,000 ago, they gouged the barren landscape and formed hollows which filled up with meltwater. Colonisation by reeds and water plants eventually led to the development of a fen, covering over any areas of open water. As these plants died and accumulated on the bottom, new plants could no longer root themselves in the mineral soil.
The plants growing round the edge of the former lake soaked up all the nutrients, leaving the centre of the fen waterlogged but poor in nutrients. These unusual conditions were perfect for the growth of sphagnum moss and the development of a bog. As the sphagnum moss grows and dies, the waterlogged nutrient-poor conditions prevent the dead plant material from decaying. The new plants simply grew on top of the dead ones and the bog started to rise! The dead plant remains are what we know as peat. In these conditions peat accumulates at about 1mm every year so bogs that have been forming for the last 10,000 years now hold up to 10 metres of peat. These domes of peat now receive all their nutrients from the rain which falls directly on them, and the structure of the peat body holds in the water to keep the system waterlogged.
